DMA, direct memory access

Looking at /proc/dma might not give you the information that you want, since it only contains currently assigned dma channels for isa devices. laudaka@Sproet:~# cat /proc/dma 1: parport0 4: cascade pci devices that are using dma are not listed in /proc/dma, in this case dmesg can be useful. The screenshot below shows that during boot the parallel port received dma channel 1, and the Infrared port received dma channel 3. laudaka@Sproet:~# dmesg | egrep -C 1 'dma 1|dma 3' [  20.576000] parport: PnPBIOS parport detected. [  20.580000] parport0: PC-style at 0x378 (0x778), irq 7, dma 1... [  20.764000] irda_init -- [  21.204000] pnp: Device 00:0b activated. [  21.204000] nsc_ircc_pnp_probe : From PnP, found firbase 0x2F8... [  21.204000] nsc-ircc, chip->init
 * http://linux-training.be/files/books/html/fun/apcs04.html